I have one thing to say. Relax. A 2 hour mash is torture, don't do it again. At about 155F you will have full conversion in about 20 minutes, it is fast. Do you have tincture of iodine? I have never done an iodine test, just 60 minute mashes and average 78% eff.
Id stir the mash once every 10-15 minutes...
This is the deal, pots are tough to mash in if you want to keep a constant temp without hassle.... that is why I have a 10 gallon cooler system, I lose about 1-2 degrees during an hour mash.
AG rocks, you will learn so much so fast! This place is great for questions.